1 pancake problem: it takes mom two minutes to bake a cake, and it takes one minute to bake both sides. At most, two cakes are put in the pot at the same time. How many minutes does it take to bake three cakes?

2. socks. There are five pairs of socks of different colors in the drawer, and the lights are not turned on. How many socks of the same color do you need to pull out?

3. Egg problem: Xiao Zhang sells eggs and a basket of eggs. The first person comes to buy half, and Xiao Zhang gives him the other half. The second man bought another half, and Xiao Zhang gave him another egg. The third man bought another half egg, and Xiao Zhang gave him another one. The fourth man came to buy half, and Xiao Zhang gave him another one, just after buying the eggs! How many eggs has Xiao Zhang always had?

4 table problem, a square table, how many corners are there after cutting off a corner?

5. Cut tofu: Cut a piece of tofu three times. How many pieces can you cut at most?

6 cut watermelon problem: cut 7 petals with three knives and leave 8 skins after eating. How to cut?

7. Bamboo pole problem: Can a 5-meter-long bamboo pole pass through the door of 1 meter?

8. Paper box problem: Can a square box with a side length of one meter put down a stick of 1.5m?

9. Clock problem: 12 hours, how many times does the clock and minute hand repeat?

10. origami problem: a piece of paper with a thickness of 1mm is folded in half 1000 times. How high is the thickness?

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